PMID- 31565581 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20231014 IS - 2167-8359 (Print) IS - 2167-8359 (Electronic) IS - 2167-8359 (Linking) VI - 7 DP - 2019 TI - Arbuscular mycorrhizal fungi alter the food utilization, growth, development and reproduction of armyworm (Mythimna separata) fed on Bacillus thuringiensis maize. PG - e7679 LID - 10.7717/peerj.7679 [doi] LID - e7679 AB - BACKGROUND: The cultivation of Bt maize (maize genetically modified with Bacillus thuringiensis) continues to expand globally. Arbuscular mycorrhizal fungi (AMF), an important kind of microorganism closely related to soil fertility and plant nutrition, may influence the ecological risk of target lepidopteran pests in Bt crops. METHODS: In this study, transgenic Bt maize (Line IE09S034 with Cry1Ie vs. its parental line of non-Bt maize cv. Xianyu335) was inoculated with a species of AMF, Glomus caledonium (GC). Its effects on the food utilization, reproduction and development of armyworm, Mythimna separata, were studied in a potted experiment from 2017 to 2018. RESULTS: GC inoculation increased the AMF colonization of both modified and non-modified maize, and also increased the grain weight per plant and 1,000-grain weight of modified and non-modified maize. However, the cultivation of Bt maize did not significantly affect the AMF colonization. The feeding of M. separata with Bt maize resulted in a notable decrease in RCR (relative consumption rate), RGR (relative growth rate), AD (approximate digestibility), ECD (efficiency of conversion of digested food) and ECI (efficiency of conversion of ingested food) parameters in comparison to those observed in larvae fed with non-Bt maize in 2017 and 2018, regardless of GC inoculation. Furthermore, remarkable prolongation of larval life span and decreases in the rate of pupation, weight of pupa, rate of eclosion, fecundity and adult longevity of M. separata were observed in the Bt treatment regardless of GC inoculation during the two-year experiment. Also, when M. separata was fed with Bt maize, a significant prolongation of larval life and significant decreases in the pupal weight, fecundity and adult longevity of M. separata were observed when inoculated with GC. However, it was just the opposite for larvae fed with non-Bt maize that was inoculated with GC. The increased percentage of larval life-span, the decreased percentages of the food utilization, and the other indexes of reproduction, growth, and development of M. separata fed on Bt maize relative to non-Bt maize were all visibly lower when under GC inoculation in contrast to the CK. DISCUSSION: It is presumed that Bt maize has a marked adverse impact on M. separata development, reproduction and feeding, especially when in combination with the GC inoculation. Additionally, GC inoculation favors the effectiveness of Bt maize against M. separata larvae by reducing their food utilization ability, which negatively affects the development and reproduction of the armyworm. Thus, Bt maize inoculated with AMF (here, GC) can reduce the severe threats arising of armyworms, and hence the AMF inoculation may play an important ecological functions in the field of Bt maize ecosystem, with potentially high control efficiency for the target lepidopteran pests. CI - (c)2019 Wang et al. FAU - Wang, Long AU - Wang L AD - Department of Entomology, Nanjing Agricultural University, Nanjing, China. FAU - Pokharel, Sabin Saurav AU - Pokharel SS AD - Department of Entomology, Nanjing Agricultural University, Nanjing, China. FAU - Chen, Fajun AU - Chen F AD - Department of Entomology, Nanjing Agricultural University, Nanjing, China. LA - eng PT - Journal Article DEP - 20190912 PL - United States TA - PeerJ JT - PeerJ JID - 101603425 PMC - PMC6745183 OTO - NOTNLM OT - Arbuscular mycorrhizal fungi OT - Food utilization OT - Growth & development and reproduction OT - Mythimna separata OT - Transgenic Bt maize COIS- The authors declare there are no competing interests. EDAT- 2019/10/01 06:00 MHDA- 2019/10/01 06:01 PMCR- 2019/09/12 CRDT- 2019/10/01 06:00 PHST- 2019/04/08 00:00 [received] PHST- 2019/08/15 00:00 [accepted] PHST- 2019/10/01 06:00 [entrez] PHST- 2019/10/01 06:00 [pubmed] PHST- 2019/10/01 06:01 [medline] PHST- 2019/09/12 00:00 [pmc-release] AID - 7679 [pii] AID - 10.7717/peerj.7679 [doi] PST - epublish SO - PeerJ. 2019 Sep 12;7:e7679. doi: 10.7717/peerj.7679. eCollection 2019.